Angle trisector



NOV. 26, 1940. NEURQHR I 2,222,853

ANGLE TRISECTOR Fiied Feb. 2, 1940 ATTORNEY Patented Nov. 26, 1940 ,v

MEN-r" I if. 2,222,853, w a TRISECTgEt as antimon ,stjicity mieit Application February2,1940,Seriall*lo.31i870 "ii-L t a clai s}; (chasin This invention relates to instruments =for'use by draftsmen, engineers, layout men; and others and by means of which angles may be quickly and accurately trisected,

One of the prime objects of the invention is to provide a simple, practical, and handy instrument which is extremely easy to manipulate, and with which any given angle can be quickly and accurately divided into three equal angles.

Another object is to design an instrument which can be economically manufactured and assembled, which is composed of relatively few parts, which can be compactly folded, and which can be manufactured in various sizes, to suit the needs of the various crafts.

With the above and other objects in view, the present invention consists in the combination and arrangement of parts, hereinafter more fully described, illustrated in the accompanying drawing, and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportion, and minor details of construction, without departing from the spirit, or sacrificing any of the advantages of the invention.

In the drawing:

Fig. 1 is a plan view of my angle trisector showing it in open position.

Fig. 2 is an edge view thereof.

Fig. 3 is a transverse sectional view taken on the line 3--3 of Fig. 1.

Fig. 4 is a diagrammatical view illustrating the trisecting of a circle by use of my angle trisector.

Referring now more particularly to the drawing in which I have shown the preferred embodiment of my invention, the numerals 5 and 6 indicate the side bars of the instrument, the inner ends of which are pivotally connected together by means of a rivet I, the-outer end sections being slotted 8 and for a purpose to be hereinafter described.

Center bars 9 and Ill respectively, are pivotally secured to the side bars 5 and 6 by means of the rivets I l, these center bars being crossed and are pivotally connected together by means of the rivet l2, said rivet including a downwardly projecting pin I3 terminating in a sharp point, which point is adapted to pierce the paper or other material (not shown) when the instrument is in use. Pins l4 and I5 respectively are mounted on the outer ends of the members In and II and terminate in a sharp point similar to that on the center pin I 3.

Guide bars or links I 6 and I! are connected to the center and side bars respectively, the inner ends of said bars being- 'piv otally connected ftogether "on a comi'non center by'means 'of the rivet menu rivet'silfland" l 9 respectively, are mounted th'e opp'o'siteend of said l'guidebars; the cylindricaI-bO'dy of'th'e rivets being 'slidably mounted in the slotted openings 8 provided in the side bars, and these rivets are freely slidable in said slots so that the instrument can be adjusted and set to trisect angles of various sizes.

In trisecting an angle, the pin I3 of the instrument is placed on a given center or the vertex of the angle to be divided and is then pressed down so that it pierces the paper or material to hold it in set position, the outer ends of the side bars are then spread or contracteduntil they define the angle to be trisected, the rivets I8 and I 9 sliding in the slotted openings 8, then by pressing on the respective rivet head I4, I5, I8, and I9, the paper or material on which the work is drawn or defined will be prick punched, the instrument is then removed and the lines for trisecting the angle can be readily drawn, it eliminates the ne cessity for frequent used a protractor, or the trial method in which a divider is used for dividing the angle into equal parts.

Referring now to Fig. 4 of the drawing in which I have shown an example of the use of the instrument. and meet without the circle, the angle produced by these lines is measured by one-half the difference of the intercepted arc; if, however, this angle is also measured by the lesser intercepted arc, then it is measured by one-third of the larger intercepted arc.

This relation is maintained by the instrument as follows: The figure produced by the outer'bars and the center bars, having all sides equal, make the opposite side and opposite angles equal. The sides of this angle from the vertex of the angle produced by the side bars to the point where the center bars are attached, are equal to the angle formed by the center bars where they intersect. These sides being equal then the opposite side must be and are parallelto each other, and if extended would still be parallel. Lines of equal length drawn between parallel lines would form similar or equal angles with these parallel lines; hence, the short upper guide bars or links which move in the slotted side bars form similar angles with the center and outer bars.,

For example, in Fig, 4 are shown two equal circles a: and y in which the various points are indicated by letters, and inasmuch as the circles are equal, the radius must also be equal, and it will therefore be obvious that F.H.=G.H;

When two lines intersect acircle E.F.=E.G; A.E.=B.E. and C.E.=C.D., also E.G. is parallel to RH. and B.E.G. is parallel to A.F.H; therefore, the angle FRI-LG, equals the angle EEG. and angle BBC. The points F and G are the points at which two equal circles intersect, whether the arc F.G. be greater or less is immaterial, as it always is one-third of the arc A.D.

From the foregoing description, it will be obvious that I have perfected a very simple, practical, and accurate instrument for use in drafting and layout rooms for trisecting angles etc.

What I claim is:

1. An angle trisector of the class described, comprising a pair of side bars pivotally secured together at their one end, center bars pivotally secured together at a point intermediate their length to form a common center, with the inner ends pivoally connected to the side bars, and links having one end pivotally connected to the common center with the outer ends slidably engaging the side bars. a

2. An angle trisector of the class described, comprising a pair of side bars pivotally secured together at the one end, crossed center bars pivotally secured together at a point intermediate their length to form a common center, with the inner ends pivotally secured to the side bars at a point spaced from the pivoting point thereof, downwardly projecting pins at the center and on the outer ends of the center bars, and links having one end pivotally connected to the common center of the center bars with their outer ends in slidable engagement with the side bars, and pins on the outer ends of said links.

3. An instrument of the .classdescribed, comprising a pair of side bars pivotally secured together at the one end and formed with elongated slotted openings in the outer free end sections thereof, crossed center bars pivotally secured together at a predetermined point inter- ,mediate their length, with the inner end of each center bar pivotally secured to one of the side bars, prickpins on the center pivot of the center bars and on the outer endsthereof, oppositely disposed links having one end pivotally secured to the center bar pivoting point, members mounted in the outer ends of the links and slidable in the slotted openings in the side bars, and pins associated with said members.

ANTHONY G. NEUROHR. 

